Life Cycle of Physalis

Physalia physalis is commonly known as the Portugese man-of-war.

The Portuguese man-of-war, or "bluebottle" as it sometimes called, is known scientifically as Physalia Physalis. It is a member of the phylum Cnidaria, which includes corals, sea anemones and jellyfish. It lives mostly on the open ocean, propelled by the wind and ocean currents. When it washes up on shore, the potent toxins stored in their tentacles may remain intact long after the death of the colony.

Classification

The top of the physalis is called a float and is normally 12 inches long with fishing tentacles averaging 30 feet in length. Physalis are pelagic, or open ocean dwellers, that are members of the "wind drift" or neuston community of organisms. The Portuguese man-of-war is in the phylum Cnidaria and class Hydrozoa. Its order is Siphonophora, its genus is Physalia and its species is physalis.

Biology

Physalia physalis is not just a single creature; it is actually a colonial organism more closely related to hydroid colonies rather than jellyfish. The top float is a single modified organism while other organisms make up the feeding tentacles. Individuals called gastrozooids perform digestion. The diet of a Portuguese man-of-war consists mostly of fish larvae and pelagic crustaceans, which are passed from the tentacles to the gastrozooids, which then digest them and pass the nutrients to other individuals through a communal gut system. The individuals are also share a communal nerve system through which they communicate.

Reproduction

The Portuguese man-of-war reproduce both sexually and asexually. Mature male and female colonies produce both eggs and sperm, which fuse to create a swimming larva. The larva then begin to reproduce asexually though budding to form a new colony of its own. When the colony is mature, it begins to produce individuals called gonozooids, the colony's the sexual organs, which produce egg and sperm from which new larva is generated.

Ecology

Physalis spends most of its life floating in the open ocean. It is hunted by sea turtles, sea slugs and sea snails, which are immune to its poison. The gas-filled sac that floats on the top of the water and acts as the colony's sail must stay wet, so periodically the colony releases the gas to submerge the sac in water. It also submerges to escape from predators. The colony typically has a life expectancy of up to a year.

Dangers

Although it is rare for humans to encounter Physalis in the open ocean, when they wash up onto shore or into intertidal zones humans may become entangled in their floating tentacles. The toxin of Physalis is dangerous to humans, causing excruciating pain and sometimes leading to death. Long after the death of Physalis the toxin can remain potent and toxic, so they should always be handled with extreme care when encountered.

References

• Life cycle of Physalia physalis
• The Indo-Pacific Portuguese Man-of-War

Resources

• Information on Physalia physalis